This invention relates to an apparatus for setting a workpiece correctly on a zipper sewing machine and more particularly to an apparatus providing presser-guide-plates to control the required sewing pattern for a zipper sewing machine.
Zipper sewing is very difficult since the positional relation between the workpiece and the zipper must be precisely set-up. For example, sewing a zipper to a skirt requires a high degree of skill since the zipper must be sewed to the biased or waistline curved portion of skirt.
FIGS. 15, 16 and 17 refer to a conventional type of zipper-skirt sewing machine. In the conventional zipper-skirt sewing machine, in order to sew a zipper F (FIG. 15) to a front cloth C1 (FIG. 16) of a skirt, a cassette 3 must first be placed on a set-table 1. The upper frame 3a of the casset 3 is opened upward. A lining cloth C2, with a zipper F previously sewed thereto, is then placed on a lower frame 3b, and the zipper F is aligned with a zipper guide 1a such that the zipper F is correctly situated. Further, the front cloth C1 is placed on the lining cloth C2 such that the to-be-sewed portions C1a, C1b are positioned on the set-table 1.
After the cloth has been positioned as indicated above, the operator must go through the following time-consuming steps:
(1) the operator steps on a pedal switch P1 activating a cylinder 4 to cause a right presser arm 7 to turn down;
(2) the end of the to-be-sewed portion C1a is set along a right pressure plate 7a such that the inner corner of presser plate 7a abuts against the end of the to-be-sewed portion C1a as shown in FIG. 17A;
(3) the operator steps on a pedal switch P1 activating a cylinder 5 to cause a left presser plate 8a to turn down;
(4) the to-be-sewed portion C1a will be set firmly on the set-table 1 as shown in FIG. 17B;
(5) the operator again steps on the pedal switch P1 releasing the cylinder 4 to cause the presser arm 7 to turn up as shown in FIG. 17C;
(6) the end of a to-be-sewed portion C1b is set along a left presser plate 8a such that the inner corner of presser plate 8a abuts against the end of the to-be-sewed portion C1b as shown in FIG. 17D;
(7) the operator steps on the pedal switch P1 to turn down the right presser plate 7a as shown in FIG. 17E;
(8) the upper frame 3a turns down and the periphery portion of the to-be-sewed portion is clamped between the upper frame 3a and the lower frame 3b, as shown in FIG. 17F;
(9) spring bodies 3C (FIG. 16) located at both sides of presser arm 7, 8 engage with stopper notches N.sub.1, N.sub.2 respectively such that the workpiece will be kept clamped between the upper frame 3a and the lower frame 3b;
(10) the operator next steps on the pedal switch P1 to turn up the presser plates 7, 8 respectively as shown in FIG. 17G, and takes out the cassette 3 with the workpiece C clamped therein, and sets on the zipper sewing machine and conducts zipper sewing to the workpiece C;
(11) a pedal switch P2 is used to step back the action executed by P1 switch when the operator desires to adjust above setting actions; and
(12) as previously mentioned, the to-be-sewed portions C1a, C1b are abutted against the corner edge of the presser arms 7, 8 respectively. Thereby, the setting of the workpiece C was much improved when compared with the former manner of judging by the human eye, and as a result, the productivity was highly increased.